chemistry journal of moldova

G. Vasile et al./Chem.J. Mold. 2008, 3 (1), 56-61hour. Hydrogen peroxide was evaporated than almost close to dry. After cooling, 25 ml 1M ammonium acetate wasadded (acidulated to pH 2 with HNO3) repeating the shaking, whizzing and washing.Results and discussionsThe determination of metal total concentration from sedimentsIn order to evaluate zinc charge, total concentrations were determinated and it was observed that in all thesediments except the first one, which is situated upstream the objectives that generates pollution as a consequence of theactivity deruled in the area, zinc concentrations overpassed the limit value (150 mg kg -1 d.w.) established by Romania’slegislation for zinc in sediments [4].Table 1Total concentrations of zinc (mg/kg d.w.) in river sediments determined within FAASSample nameZn ConcentrationSample location(mg/kg d.w.)1 Baiaga River 134,82 Baiaga River 366,383 Baiaga River 389,64 Baiaga River 381,745 Baiaga River 715,856 Baiaga River 432,37 Paraul Baiaga 387,68 Coranda River 680,89 Ciongani River 494,6810 Quarry water 494,75Zinc partitioning in sedimentsBecause only a part of the total quantity of heavy metals from the sediments can be considered bioaccesible,labile, mobile and potentially toxic for the environment, the total concentrations of metals are not enough for theestimation of heavy metals pollution stat. This is the reason for which it was made the study of zinc partitioning in thesediments by applying BCR extraction procedure[5-7].This procedure allows zinc concentrations partition into the following fractions:Easy soluble fraction: this fraction contains the metal connected to carbonates or absorbed to the surface andmetallic-organic complexes in which the metal in weakly connected.The fraction connected to iron or manganese oxides.The fraction connected to organic combinations.Zinc concentrations from 1-3 steps were summed and compared to the total concentration. The results referringto zinc partition in the sediments from the mining area are presented in figure 3.Fig. 3. Partitioning of Zn in river sediments59